## PSN-L Email List Message

From: ChrisAtUpw@.......
Date: Thu, 13 Mar 2008 13:33:37 EDT

```In a message dated 2008/03/13, tchannel1@............ writes:

> Good question, and here's what I found:   I had this issue on the copper
> vertical, the bottom hinge is where I tried to use a roller on roller, then I
> tried a foil hinge.
> Both failed big time.  Because of the forces and the different angles of
> pressure, the roller on roller keep sliding off.

Hi Ted,

You must have made the arm too heavy or the mass too light, possibly
got the bearing angle wrong or done something. I have NEVER had a problem,
either with ball on a plate or with crossed rollers. With a crossed roller you put
the vertical roller on the frame. With ball on a plane, the ball goes on the
upright, the plane on the end of the arm.
The vertical load on the end bearing is far less than the friction due
to the axial load mass / sin(angle). If the angle is 30 deg, you will have a
push of 2Mg, so if the friction were only 0.5, you would need a vertical force
equal to the mass to displace it!

Regards,

Chris Chapman
In a me=
ssage dated 2008/03/13, tchannel1@............ writes:

Good question, and here's what=20=
I found:   I had this issue on the copper vertical, the bottom hin=
ge is where I tried to use a roller on roller, then I tried a foil hinge.
Both failed big time.  Because of the forces and the different angles=20=
of pressure, the roller on roller keep sliding off.

Hi Ted,

You must have made the arm too heavy or=
the mass too light, possibly got the bearing angle wrong or done something.=
I have NEVER had a problem, either with ball on a plate or with crossed rol=
lers. With a crossed roller you put the vertical roller on the frame. With b=
all on a plane, the ball goes on the upright, the plane on the end of the ar=
m.
The vertical load on the end bearing is=
far less than the friction due to the axial load mass / sin(angle). If the=20=
angle is 30 deg, you will have a push of 2Mg, so if the friction were only 0=
..5, you would need a vertical force equal to the mass to displace it!

Regards,

Chris Chapman
```